Double telescope



June l0 1924l H. ERFLE DOUBLE 'I'EzLEscoPEf Filed Aug. 1:5. 1921 2 Sheets-Sheet 2 Patented .lume 10, 1924,

sms me Q ERFLE, F ENA, GERMANY, ASSIG-NOR TO THE FIRM 0F CARL ZEIS8, 0F

` 1,497,294 FFlcE.

JENA, GERMANY.

:DOUBLE 'rEnEscorn Application ledAugust 13, l1921. Serial No. 492,113.

(GRANTED UNDER THE PROVISIONS 0F THE ACT OF MARCH 3, 1921, 41 STAT L., 1813.)

To all whom it may concern.'

Bc it known that I, HEINRICH ERFLE, citizen of the German Empire, Jena, Germany, have invented useful Double Telescope (for which I have iledan application in Germany, June 10, 1918), of which the following is a specication.

The present invention relates to double l@ telescopes in which the ocular -distance can be adapted to the interpupillary distance j without a change of the position of the optical parts, lying in front of the, oculars.

In the said telescopes, a sub-species of 115 which is, e. g., described in the` patent specication 947971, the ocular-axes do not geny erally coincide with the axes of the images reduced by the objectives (hereafterbriefly' enoted as the image-axis), the position of 2@ the ocular-axes generally being such, that the ray cils, entering parallelly to each other the objectives, form an angle with each other when emerging from the oculars. Hence, withthe observation through a telescope of the said kind, the axes of the eyes.

must generali be forced into unnatural positions in whlch, with relaxed accommodation, they are inclined to each` other, which will be articularly troublesome if the axes t@ diverge 1n the direction of vision.

rIhe object of the invention is to improve the said'telescopes in such a Way that also with any position of the oculars it will not be necessary to force the axes of the eyes h into the said unnatural position. According to the inventionfthe above object is attained 'b disposing behind each of the oculars a g ass wed e rotatable about an axis, which 1s paralle to the optical axisl of the e@ respective ocular and by so coupling it to the latter that it is rotated when changing the distance apart of the oculars. By a suitable dis osition and rotation of the wedges it can tgen be attained that the ray pencils axially entering the objectives are emerging from the telescope, to which in that case also the Wedges are appertaining, parallel to each other or at least approximately parallel in any ositions of the oculars.v y

In t e annexed drawing Figs. 1 and 2 show. the theoretical principles of the invention.y Fig. 3 is a front view of a telescope i according tothe invention. Fig. 4 is a section, Fig. 5 .a-front View of another tele-` a scope., Fig. 6 isV partly a side view and residing at. partly a section of the telescope.

a new and In which way the dependency of the rota-` tion of the Wedge upon the amount of the relative displacement of the oculars is to be chosen and in which manner the simultaneous rotation of the wedges and the relative displacement of the oculars may be realized, i's illustrated hereafter with the aid of the Figs. 1 and 2 for oculars havin collective effect, whereby it may be mentioned that the said'explanations may also be applied accordingly to. oculars having dlspersive eii'ect. In Fig. 1 the two image axes of a double, telescope which have the lixed distance apart Z0 be denoted by 1- 1 and 2. Let B-B be the trace of the focal planes of the objectives, coinciding with the front focal planes of the'oculars and C-C the trace of the chief planes of the'two oculars which, for simplicityssake, are assumed to be very thin. The distance between the chief planes of the oculars and their focal planes is denoted by f. In addition, let the axes of the oculars coincide in a medium position with the corresponding image axes and, besides, it may be anticipated'that, for adapting the ocular disof inclination which the said ray pencils,

after having traversed the oculars, embrace with the image axes may thereby be approximately computed at i 4By the said angle the wedges, to be disposed l los . i if the said pencils are to be directed paralo limits a comparatively good approximation the plane of lelly by them. By denoting by c: the deexion which a ray of light undergoes in the main section of the wedge when hitting this wedge at a certain angle, e. g. such as 90, the approximate amount of delexion in the plane of the image axes, which may be denoted as lateral deflexion, will be ca -:a: sin cp '.-lo (3) a sin p=2 I and consequently the an lethrough which the Wedge is to be rotate if the distance of the oculars be altered by the value Z-Zo will be (3*) fp=arcsin -2-a rIhe simultaneous rotation of the wedge through the said angle with'a rectilinear displacement of the oculars requires, however, a comparatively complicated actuating mechanism. The device will become simpliiied by so choosing the rotation of the wedge that in dilerent positions of the oculars the angles q are in the same proportion to each other as the differences l-Z, corresponding to the said positions. As may be easlly seen, o the said device still affords within certain to the law expressed by the e uation 3, so that such a device is also app icable. The position of the axes of rotation of the wedge is suitably so chosen that they coincide with the optical axes of the oculars.

If the adaptation of the ocular distance to the interpupillary distance be not effected by a displacement of the oculars arallel to the image axes but y a rotation of each of the oculars about 'an axis, lying outside its optical axis, as such is, e. g. the casein the device according to the above mentioned patent speciication 947 ,971, a particularly good compensation of the rela- -tive inclination of the axial ray pencils,

.. coincide with one of the axes of rotation of is equal to that of the oculars and by choosing, contrary to -the said patent4 specification, the position of the axes of rotation 'of the oculars in such a manner that the distance of the latter axes the image axes, in which case a symmetrical position of the oculars relative to an intermediate plane, assumed to lie between the image axes and perpendicular to the plane of the latter, is again anticipated. In any positions of the oculars a complete compensation with the approximation, obtained as illustrated in detail in Fig. 2 of the drawing. In the said-figure the ima e axes Alf-A1 and A2 are assumed to ge perpendicular to the drawin plane, the distance apart of the said axesgbeing again denoted by Zo. Let M1 and M2 be the points of intersection of the axis of rotation for the oculars with the plane of the image axes. Let each of the axes of rotation of the oculars be at the distance fr from the optical axis of the corresponding ocular, in the present case the disposition being vso chosen that the cylindrical surfaces, on which the optical axes of the oculars are moving, surround the image axes. Moreover, let o, be

the angle, which the plane containing the axis of rotation of the left ocular and the opticalvaxis of the latter, embraces with the plane containing the axis of rotation of the same ocular and the appertaining image axis, and q2, ,the'corresponding angle of the right ocular. For any position of the oculars, in

which their optical axes have the distanceapart Z, the relation l-l., 2r

then holds good. By so disposing the wedges behind the oculars that one each of the optical axes. of the oculars andthe appertaining axis of rotation of the ocular coincide in a rincipal section of the respective wedge, t e angles o, and cp, are simultaneously those angles which embrace at lany one time the principal sections of the wedges with a plane, which is perpendicular to the plane containing the two image axes, and which contains one `of the image axes. Hence, in the present case the condition expressed in the equation (3) is always entirely fulfilled. if i l-lo Z-'lo a 2r 2f (5) y 1=af, s i. e. ifonly to the radius 1- a certain value be iven which depends on the deiexion of 51e wed e in the main section and the focal lengt of the ocular. In addition, it may be mentioned that in the case just dealt with, when computing the amount of inclination of the axial pencils to be removed by thewedges, the angles have to be taken into consideration which those strai ht lines embrace with the image axes whic unite the oints of intersection (l)l and P2 respective y) of the image axes with the front focal lanes of the oculars and the projections o the corresponding o tical centresv (O and O respectively) o the valid for the equation 3, 1s then ocu1ars, .and that for the said angles. the

same relations take elect as for. the angles and @2 inthe first mentioned case ofthe ocular displacement.

By rigidlyfc'onnecting in the case, just.

alluded to theiwedges with the ocular tubes, for the simultaneous adaptation of the ocu; 'lar distance to the i'nterpupillary distance .'tive inclinations of the ray pencils, axially of the axis :of rotation of the oculars "be smaller or, asin the device according-to j .entering the objectives, althoughbeing less- 'perfect than 4in the case just referred if to, .can naturally also be attained if the distance .the patent specification 947,971, largertl'ian the; distance of the image axes.

In .allcases referred to, the ray pencils observed are naturally onlydirected par# i f-allelly' to eachother bythefwedges,.whilst there .still .remains aninclination. of the said'pencils'relative to Athe hei ht, which does nothave, however,- any trou lesorne'ef 1 feet, since no relative difference in the. height of both images takes place..-

` In the first constructionalexample (Figs' 34 and 4) there are fixed parallelly to each other 'on a'casing a, containing the two oli-.- Jectives-b. at a fixed distance apart c, three' guidebars dhd, da, between which the two oculars are-dis' laceably disposed parallelly i A2-" 2. Each of the ocularsconsistsof an eye lens c14 and a collective lens e2, 'which are both fixed with-in a,tube e2' Tli'e said tube "is so disposed within a socket ,.that. itcan b e shifted within' the lattermjthe. direction of its axis-but not be` rotated relative to the socket, for which purposejit is -pro'- vided'wfith esides, toeach of thesockets', f a' toothed 'gages in one oftwo racks h1 and h2, 4 bot-hscrewed to the guide bard, and each 'of the.

sockets 'gis-provided with two extensions g1 and g2 wit a female thread. 1-he arms of. both oculars engage in a screw spindle z, provided 'with a .r1 htV andleft-handed thread and' rotatably isposed on-the casing a.. Finally, wit-hineach ofthe tubes `e thereI `is `fastened an achromatic glasswedgel e* be- "Thereby, the: sockets gand along .witli'them the two .oculare are either moved towards al pin e? engagin' in a' slit fl a of the socket f. Tlie latter in its turn. `rotatably disposed within a second socket gg, which isprovided-witha p rismatic guide,

opposite direction.

lH E'I-imieir' ERFLE. f

eachl 'other or awayffroin each other, ac-

cording to the spindle being rotated ,in the one or the other direction'. Owing to the.

motion of the sockets g, thel -toothedsegments f2 aire rolling off the racks h1 antik, so that simultaneously with .the displace.- nient of the oculars a rotationof the same and' thereby oftheglass wedges e* takes place. "lhe focussing ofl the oculars relative to sharpness of theimageis effected by axially displacing the tubes c in thesocketl I f In" the second constructional exanip theobjectives, two guide ringsZ are fixe Q (Figs. 5 and 6) on'a 'casing 7c, containing.

in each of. vwhich a socket m is rotatably dis'f posed which contains anl axially shiftable i but v Within lthe socket non-rotatableoculartn be n with a collective lens nl, an eye ylens ai? and an -achromatic 'wedge 11.3,. Each of thcvsockets m carries ka worm-wheel segment ml and with both segments there meshes adriving baro, provided withboth a` ri ht and a left-handed thread and rotatably is:

posed onthecasing k. Besides, the guide rings AZ are eccentrically disposed relative to openings. p, which concenti'ically. 'surround theimage axes A1' A1L `and A2 A whereby the margins'- vof the openings act as .diaphragms of the field of view. The-dis", .tance apart of. the 'axes M1 'and M2 of the Ito the distance guide rings is'chosen equal apart of the images axes.

' 'By-*then giving the-drivingbar o a vro -tary mot-ion. there'is caused -again beside a' to the plane o the n nageaxes Alf-A1 and;-

change of the distance apart of theoculars,

a vsinniltaneous rotation of the same and thereby of the wedges n. The focussing of' theoeulars. relative toshar ness of the im.

age is, -alsoin this 'case e ected againV by` the sockets 'I-c-laimrf 1. In a double "telescope two oc u'lars,` a

glass wedge, rotatablydisposed behind each of these oculare' about'an axis'parall'el to distance apart ofthe oculars, 'and `means for coiiplingftheV said glass wedge to the 'respective ocular so Aas tobe rotated'when changing the distance apart of the oculars.

2.-'In a, .double telescope twooculars, each of Whichis rotatably disposed about an axis an axiaLdisplac-cmen-tof the oculars within mi no the ocular axis, "means for changing the lying outside its o tical axis, a rotatable glass' wedge fitted behind each-of these oculare,

'Witnessesf PAUL KRoEn, l BICHARUHAHN. 

